Growth Calculator

The Growth Calculator helps wildlife carers track whether an animal is growing normally by comparing actual measurements against published scientific growth curves. It includes a birth date estimator, interactive growth charts, and weight-for-age (WFA) tracking.

Overview

Wildlife rehabilitation depends on regular measurements to assess whether an animal is developing on track. Without a baseline to compare against, it is impossible to know if an animal is underweight, growing too slowly, or ready for release. The Growth Calculator provides that baseline using published research data for Australian species.

What It Does

1. Growth Chart -- plots actual weight (red line) vs predicted weight (blue line) over the animal's age in days
2. Weight For Age (WFA) -- calculates the difference between actual and predicted weight at each measurement, colour-coded to flag animals falling behind
3. Birth Date Estimator -- estimates an animal's date of birth from physical measurements when the DOB is unknown

Supported Species

Growth reference data is included for the following species, sourced from peer-reviewed publications:

Species Group	Species	Reference
Macropods	Eastern Grey Kangaroo	Poole et al. 1982; ARAZPA
	Common Wallaroo	ARAZPA
	Red-necked Wallaby	ARAZPA
	Swamp Wallaby	ARAZPA
Possums	Common Brushtail Possum	Kerle 1984
	Common Ringtail Possum	How 1983
Flying Foxes	Grey-headed Flying Fox	Divljan 2006; Hall & Richards 2000
	Little Red Flying-fox	Hall & Richards 2000

Reference data covers both male and female growth curves for each species.

Growth Tab

The Growth tab appears on every animal's detail page, alongside Care Records and other tabs.

Recording a Measurement

1. Navigate to the animal's detail page
2. Click the Growth tab
3. Scroll to the Add Growth Measurement form
4. Enter the date of the measurement
5. Enter the weight in grams and any body measurements in millimetres
6. Add optional notes
7. Click Add Measurement

Available Measurements

Field	Unit	Used By
Weight	grams	All species
Head Length	mm	Macropods, possums
Ear Length	mm	Macropods, possums
Arm/Forearm Length	mm	All species (primary for flying foxes)
Leg Length	mm	Macropods, possums
Foot Length	mm	Macropods, possums
Tail Length	mm	Macropods, possums
Body Length	mm	Macropods, possums
Wing Length	mm	Flying foxes only

The form automatically shows only the fields relevant to the animal's species type.

Growth Chart

When an animal has a date of birth and at least one weight measurement, the Growth Chart displays:

• Red line (Actual Weight) -- the animal's recorded weights plotted over age in days
• Blue line (Predicted Weight) -- the expected weight curve from the reference data for that species and sex

This allows carers to see at a glance whether an animal is tracking normally, above, or below expected weight.

info

The growth chart requires a date of birth. If the animal's DOB is unknown, use the Birth Date Estimator (see below) to estimate one first.

Weight For Age (WFA)

The growth history table shows a WFA column for each measurement:

• WFA = Actual Weight - Predicted Weight at the animal's age on that date
• Positive values (e.g., +120g) mean the animal is above predicted weight
• Negative values (e.g., -85g) mean the animal is below predicted weight

WFA Colour Coding

Colour	Meaning
Green	Within 10% of predicted weight -- on track
Amber	10--20% below predicted -- monitor closely
Red	More than 20% below predicted -- intervention may be needed

Birth Date Estimator

When an animal's date of birth is unknown (common for orphaned joeys found in the field), the Birth Date Estimator can estimate it from physical measurements.

How It Works

1. The estimator appears automatically on the Growth tab when an animal has no date of birth and the species has reference data
2. Enter the date the measurement was taken and one or more measurements (weight, foot length, arm length, etc.)
3. Click Estimate Birth Date
4. The system looks up the reference data to find what age corresponds to each measurement using linear interpolation
5. If multiple measurements are provided, it takes the median of the individual estimates for robustness
6. Click Apply Birth Date to Animal to save the estimated date of birth

Example

A Red-necked Wallaby joey is found and weighed at 830g with a foot length of 111mm on 15 June 2024:

• Weight 830g maps to approximately age 230 days in the reference data
• Foot length 111mm also maps to approximately age 230 days
• Estimated birth date: 28 November 2023 (230 days before 15 June 2024)

Admin: Growth Reference Data

Administrators can view the growth reference data under Admin > Growth Data:

• Browse reference data by species and sex
• View age, weight, and body measurement data points
• See the source citation for each data set

Growth reference data is loaded automatically via database migrations on deployment. It is system-level data shared across all organisations.

Data Sources & References

The growth reference data used in WildTrack360 is sourced from published scientific literature:

Macropods

• Poole, W.E., Carpenter, S.M. & Wood, J.T. (1982). "Growth of grey kangaroos and the reliability of age determination from body measurements. I. The Eastern Grey Kangaroo, Macropus giganteus." Australian Wildlife Research, 9(1), 33-49.
• ARAZPA (Australasian Regional Association of Zoological Parks and Aquaria). "Birth Date Determination in Marsupials" -- growth rate tables for kangaroos, wallabies, and wallaroos.

Possums

• Kerle, J.A. (1984). "Growth and development of Trichosurus vulpecula (Marsupialia: Phalangeridae)." In A.P. Smith & I.D. Hume (Eds.), Possums and Gliders, Australian Mammal Society.
• How, R.A. (1983). "Growth and development of the common ringtail possum, Pseudocheirus peregrinus." In A.P. Smith & I.D. Hume (Eds.), Possums and Gliders, Australian Mammal Society.

Flying Foxes

• Divljan, A. (2006). "Population ecology of the grey-headed flying fox, Pteropus poliocephalus." PhD thesis, University of Sydney.
• Hall, L.S. & Richards, G.C. (2000). Flying Foxes: Fruit and Blossom Bats of Australia. UNSW Press, Sydney.

note

Growth reference data represents average values for normal healthy development. Individual animals may vary. Always use clinical judgement alongside the calculator.